The typical prior art parts washers are used to remove dirt, grime, etc. from the mechanical parts and comprise a sink mounted over a collection tank and a pump and conduit system to circulate the cleaning solvent from the collection tank to the nozzle of the sink. The worker cleans the parts in the sink and the cleaning liquid drains from the sink into the collection tank.
Over time, the liquid cleaning solvent used to remove dirt, grit and grease from the parts being washed will become saturated with the dirt removed from the mechanical parts and the cleaning solvent loses its effectiveness. Filters have been placed in parts washers to receive the dirty cleaning solvent draining from the sink under gravity pressure prior to passing into the collection reservoir. Also, filters have been placed in the conduit between the pump and the faucet. U. S. Pat. No. 3,378,019 to C. R. Riolo, et al. discloses a parts washer having a cylindrical filter cartridge mounted inside its reservoir below the sink, and the sink is removably mounted over the reservoir. The solvent moves through the gravity drain opening of the sink and through the filter before it returns to the reservoir. Similarly, U. S. Pat. No. 3,522,814 to Olson discloses a parts washer having a pump for moving cleaning solvent from a reservoir through a faucet which directs cleaning solvent into a sink and upon the parts to be washed, whereupon the cleaning solvent then drains by gravity through the bottom of the sink into a lower catch basin. A filter body containing waste cotton or a similar material filters the liquid cleaning solvent before it returns back to the reservoir.
U.S. Pat. No. 4,128,478 to Metzger discloses a cylindrical filter assembly in a parts washer cleaning cabinet. Metzger teaches the liquid cleaning solvent being drawn from the reservoir and passed through a cartridge filter prior to passing through a faucet to the sink.
All of the prior art devices cited above represent earlier attempts to deal with the problem of effectively cleaning the liquid cleaning solvent used in mechanical parts washers, in an attempt to improve the performance and increase the life of the cleaning solvent. There are, however, inherent drawbacks in the known prior art. For example, in both Riolo and Metzger, the filter cartridge assembly is located within the reservoir. Both require substantial disassembly of the sink from the reservoir in order to replace or clean the filter. Also, both of these filter cartridges are gravity filters, and do not receive cleaning solvent from the sink under pressure greater than atmospheric to permit high pressure filtration. Olson does not teach the use of a filter cartridge assembly, only a mass of filter material, such as cotton, disposed in a filter body.
Lastly, both Riolo and Metzger teach a parts washer in which the reservoir is located within a cabinet which supports a sink, and the sink must be removed from the cabinet in order to gain access to and remove and replace the filter cartridge. Olson presents a simpler solution to this problem in providing a sink and filter body which are mounted on a reservoir barrel, but Olson does not provide a filter cartridge for cleaning the liquid cleaning solvent.
None of the known prior art parts washers disclose a mechanical parts washer for cleaning mechanical parts and providing an easily removable filter cartridge for filtering the liquid draining from the sink as well as a means for occasionally directing the liquid cleaning solvent under greater than atmospheric pressure through the filter cartridge to clarify and prolong the life of the cleaning solvent.